JP2006228632A - Piping structure of fuel cell stack - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To exhaust gas or water contaminating piping without staying in the piping structure of a fuel cell stack. <P>SOLUTION: The piping structure 1 of the fuel cell stack is such that a cooling water outlet connection part 24 connecting cooling water outlet piping 6 exhausting cooling water from the fuel cell stack 2 and the fuel cell stack 2 is installed in the position higher than a cooling water passage in the fuel cell stack, a fuel gas outlet connection part 64 connecting fuel gas outlet piping 5 for exhausting fuel gas and the fuel cell stack 2 is installed in the position lower than a fuel gas passage in the fuel cell stack, and an oxidant gas outlet connection part 44 connecting oxidant gas outlet piping 8 for exhausting oxidant gas and the fuel cell stack 2 is installed in the position lower than an oxidant gas passage in the fuel cell stack. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fuel cell stack piping structure, and more particularly to a fuel cell stack piping structure configured to discharge gas mixed in cooling water without stagnation.

  A solid polymer electrolyte fuel cell is composed of an electrolyte membrane composed of an ion exchange membrane, a fuel electrode disposed on one surface of the electrolyte membrane, and an air electrode disposed on the other surface of the electrolyte membrane. A unit fuel cell is formed by installing a separator serving as a flow path for supplying fuel gas and oxidant gas to the fuel electrode and air electrode of the membrane-electrode assembly, respectively. Since the generated power of this unit fuel cell is as low as 1 V or less, usually, a plurality of unit fuel cells are stacked to form a fuel cell stack, which is used by being mounted on a vehicle, for example.

  In a solid polymer electrolyte fuel cell, a reaction (H2 → 2H + + 2e-) occurs in which hydrogen becomes hydrogen ions and electrons on the fuel electrode side, and oxygen and hydrogen ions that pass through the electrolyte membrane on the air electrode side. A reaction (2H + + 2e-+ (1/2) O 2 → H 2 O) occurs in which water is generated by electrons traveling around the external circuit.

  In order for these reactions to be performed normally, it is first necessary that the hydrogen ions be humidified to some extent so that they can move through the electrolyte membrane to the air electrode side. In addition, the water generated from the gas flow path (especially the oxidant gas flow path) in the fuel cell stack is appropriate so that the water droplets generated by the reaction at the air electrode do not hinder the supply of the oxidant gas to the air electrode. It is also necessary to discharge the fuel cell outside. Furthermore, it is also necessary to prevent air from flowing into the cooling water flow path in the fuel cell stack so that the heat generated by the reaction at the air electrode can be effectively cooled.

  In addition, each fuel cell piping is used to measure the pressure, temperature, etc. of each of these fluids to optimally control the state of the gas flowing into the fuel cell, thereby improving the life of the fuel cell and improving the power generation performance. It is necessary to install various sensors.

Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-343400 (Patent Document 1), in the connection piping structure to the fuel cell stack, the outlet position of the cooling water piping is set higher than the through manifold of the fuel cell. It is set to improve the air escape characteristics in the cooling water piping. Further, the piping outlet position of the oxidant gas and the fuel gas is set to a position lower than the through manifold of the fuel cell so as to improve water drainage.
JP 2002-343400 A

  However, in the conventional example disclosed in Patent Document 1 described above, since only the positional relationship between the connection position of each fluid and the through manifold of the fuel cell stack is defined, for example, depending on the state of the internal flow path in each cell, There is a problem in that an air pool is generated in the cooling water flow path in the fuel battery cell, the air escape property is deteriorated, and the cooling performance is deteriorated. In addition, there is a problem that generated water is accumulated in the oxidant gas flow path, drainage performance is deteriorated, and power generation efficiency is reduced due to flooding.

  In addition, when multiple fuel cell stacks are stacked in the vertical direction, the connection position of the fuel cell piping is not specified, so depending on the connection position, problems such as reduced cooling performance and reduced power generation efficiency may occur. Could happen.

  Furthermore, since the fuel cell piping of each fluid overlaps vertically, various sensors that measure the temperature, pressure, etc. of the gas flowing into or out of the fuel cell stack are installed in the vicinity of the fuel cell inlet / outlet. It was difficult. For this reason, depending on the piping structure from the sensor installation position to the fuel cell, an error may occur between the sensor reading and the actual value at the fuel cell inlet / outlet, shortening the life of the fuel cell or making the fuel cell more efficient There was a problem that it could not generate electricity well.

  In order to solve the above-described problems, a fuel cell stack piping structure according to the present invention includes a fuel cell stack piping structure that supplies fluid to the fuel cell stack, and a cooling water outlet pipe that discharges cooling water from the fuel cell stack. The cooling water outlet connection between the fuel cell stack and the fuel cell stack is installed at a position higher than the cooling water flow path in the fuel cell stack.

  In the fuel cell stack piping structure according to the present invention, the cooling water outlet pipe for discharging the cooling water from the fuel cell stack and the cooling water outlet connecting portion for connecting the fuel cell stack are arranged more than the cooling water flow path in the fuel cell stack. Since it is installed at a high position, the flow of the cooling water discharged from the fuel cell stack can be constantly increased. Accordingly, the gas mixed in the cooling water can be discharged outside the fuel cell without stagnation, so that the cooling performance of the cooling water can be improved and the power generation performance and life of the fuel cell stack can be improved.

  Hereinafter, an embodiment that is the best mode for carrying out the piping structure of the fuel cell stack according to the present invention will be described.

  FIG. 1 is a perspective view showing the configuration of the piping structure of the fuel cell stack according to the present embodiment.

  As shown in FIG. 1, the fuel cell stack piping structure 1 of this embodiment includes a fuel cell stack 2 that generates electric power by reacting a fuel gas and an oxidant gas by an electrochemical reaction, and an oxidant in the fuel cell stack 2. An oxidant gas inlet pipe 3 for supplying gas, a cooling water inlet pipe 4 for supplying cooling water to the fuel cell stack 2, a fuel gas outlet pipe 5 for discharging fuel gas from the fuel cell stack 2, and a fuel cell stack 2 A cooling water outlet pipe 6 for discharging cooling water from the fuel cell, a fuel gas inlet pipe 7 for supplying fuel gas to the fuel cell stack 2, an oxidant gas outlet pipe 8 for discharging oxidant gas from the fuel cell stack 2, A fuel cell manifold 9 that connects piping to the fuel cell stack 2 and various sensors 13 to 18 installed in each piping are provided.

  Here, the fuel cell stack 2 is configured by stacking a plurality of unit fuel cells in the horizontal direction. Hydrogen gas, which is a fuel gas, is supplied to the anode of each unit fuel cell, and the cathode is supplied to the cathode. Electric power is generated by an electrode reaction in an electrolyte membrane that is supplied with air as an oxidant gas and is sandwiched between an anode and a cathode. Each unit fuel cell is provided with a cooling water flow path to cool the unit fuel cell that has generated heat by an electrochemical reaction.

  The oxidant gas inlet pipe 3 is connected to the upper stage of the fuel cell manifold 9 and supplies the oxidant gas to the fuel cell stack 2.

  The cooling water inlet pipe 4 is connected to the middle stage of the fuel cell manifold 9 and is arranged so as not to overlap with the oxidant gas inlet pipe 3 so as to supply cooling water to the fuel cell stack 2.

  The fuel gas outlet pipe 5 is connected to the lower stage of the fuel cell manifold 9 and is disposed so as not to overlap with the oxidant gas inlet pipe 3 and the cooling water inlet pipe 4 so as to discharge the fuel gas from the fuel cell stack 2. is doing.

  The cooling water outlet pipe 6 is connected to the upper stage of the fuel cell manifold 9 and discharges the cooling water from the fuel cell stack 2.

  The fuel gas inlet pipe 7 is connected to the middle stage of the fuel cell manifold 9, is disposed so as not to overlap with the adjacent cooling water outlet pipe 6, and supplies the fuel gas to the fuel cell stack 2.

  The oxidant gas outlet pipe 8 is connected to the lower stage of the fuel cell manifold 9 and is disposed so as not to overlap the adjacent fuel gas inlet pipe 7 and the coolant outlet pipe 6 so as to be oxidized from the fuel cell stack 2. The agent gas is discharged.

  The fuel cell manifold 9 is connected to fuel gas, oxidant gas, and cooling water piping, and supplies and discharges each fluid to the fuel cell stack 2.

  Each sensor 13-18 is a detection means for detecting the pressure, temperature, etc. of the fluid which flows in the piping, and is installed in the upper part of each piping, and the detection part is facing downward. Thereby, it is possible to prevent water from collecting in the detection unit, and to prevent freezing or poor control of the gas pressure when left in a low temperature environment. Further, when the fuel cell system is installed under the floor of the vehicle, if the auxiliary equipment side connection position of the fuel gas and oxidant gas piping discharged from the fuel cell stack 2 is always set to a low position on the external manifold side, Water stays in the fuel cell connection pipe, and it is possible to prevent damage to the pipe due to freezing in a low temperature environment and shorten the start-up time of the fuel cell. At this time, the water accumulated at the outlet portion of the fuel cell external manifold can be discharged, for example, by installing a fuel gas and oxidant gas discharge means in the part and mixing it with the exhaust gas. An adverse effect on power generation of the fuel cell can be prevented. Of course, it is possible to aim for the same effect even if the same installation method is adopted in the compartment space of the front part of the vehicle.

  Next, how each fluid flows in the piping structure 1 of the fuel cell stack of the present embodiment configured as described above will be described. However, the arrow shown in the fuel cell stack schematically represents one of a plurality of flow paths.

  First, the flow of cooling water will be described with reference to FIGS. FIG. 2 is a diagram for schematically explaining the flow of cooling water in the fuel cell stack 2. As shown in FIG. 2, the cooling water supplied from the cooling water inlet pipe 4 (FIG. 1) flows into the fuel cell manifold 9 from the cooling water inlet connection portion 21 installed in the middle stage of the fuel cell manifold 9 and is cooled. It is sent to the water inlet channel 22. Then, the cooling water is supplied from the cooling water inlet channel 22 to each unit fuel cell, passes through the cooling water channel in the unit fuel cell, cools the unit fuel cell, and goes to the cooling water outlet channel 23. And cooling water is discharged.

  Here, the flow of the cooling water in the fuel cell will be described with reference to FIG. As shown in FIG. 3, the cooling water supplied from the cooling water inlet channel 22 installed in the middle stage flows through the cooling water channels 32 installed in the upper and lower portions in the fuel cell 31 and is installed in the upper stage. The cooling water outlet channel 23 is discharged.

  Here, as shown in FIG. 3, the coolant outlet channel 23 is installed at a position higher than the coolant channel 32 in the fuel cell. Therefore, the flow of the cooling water is a flow that rises from the cooling water flow path 32 in the fuel cell to the cooling water outlet flow path 23, and the gas (mainly air) mixed in the cooling water flow path 32 is allowed to flow into the cooling water outlet flow. It can be discharged to the path 23.

  Further, as shown in FIG. 2, the cooling water discharged to the cooling water outlet channel 23 is sent to the fuel cell manifold 9 and discharged from the cooling water outlet connection portion 24 to the cooling water outlet pipe 6.

  At this time, since the cooling water outlet connection portion 24 is installed in the upper stage, the cooling water outlet connection portion 24 is positioned higher than the cooling water outlet channel 23. Therefore, the flow of the cooling water is a flow that rises from the cooling water outlet passage 23 to the cooling water outlet connection portion 24, and the gas mixed in the cooling water passage 32 can be discharged to the cooling water outlet pipe 6. it can.

  Next, how the oxidant gas flows will be described with reference to FIGS. 4 and 5. FIG. 4 is a diagram for schematically explaining the flow of the oxidant gas in the fuel cell stack 2. As shown in FIG. 4, the oxidant gas supplied from the oxidant gas inlet pipe 3 (FIG. 1) flows into the fuel cell manifold 9 from the oxidant gas inlet connection portion 41 installed at the upper stage of the fuel cell manifold 9. Then, it is sent to the oxidant gas inlet channel 42. An oxidant gas is supplied from the oxidant gas inlet channel 42 to each unit fuel cell, and is supplied to the cathode through the oxidant gas channel in the unit fuel cell. At the cathode, there is a reaction (2H + + 2e-+ (1/2) O 2 → H 2 O) that produces water by the supplied oxygen, hydrogen ions that permeate the electrolyte membrane, and electrons that have traveled around the external circuit. Done. The oxidant gas remaining without being consumed and the water vapor generated by the reaction are discharged to the oxidant gas outlet channel 43.

  Here, the flow of the oxidant gas in the fuel cell will be described with reference to FIG. As shown in FIG. 5, the oxidant gas supplied from the oxidant gas inlet channel 42 installed in the upper stage flows through the oxidant gas channels 52 installed in the upper and lower portions in the fuel cell 51, It is discharged to an oxidant gas outlet channel 43 installed at the lower stage.

  Here, as shown in FIG. 5, the oxidant gas outlet channel 43 is installed at a position lower than the oxidant gas channel 52 in the fuel cell. Therefore, the flow of the oxidant gas is a flow that descends from the oxidant gas flow path 52 in the fuel cell to the oxidant gas outlet flow path 43, such as generated water contained in the oxidant gas flow path 52. Water droplets can be discharged to the oxidant gas outlet channel 43.

  Further, as shown in FIG. 4, the water droplets discharged to the oxidant gas outlet channel 43 are sent to the fuel cell manifold 9 and discharged from the oxidant gas outlet connection portion 44 to the oxidant gas outlet pipe 8. .

  At this time, since the oxidant gas outlet connection portion 44 is installed in the lower stage, it is positioned lower than the oxidant gas outlet channel 43. Accordingly, the flow of the oxidant gas is a flow that descends from the oxidant gas outlet channel 43 to the oxidant gas outlet connection 44, and water droplets such as generated water contained in the oxidant gas channel 52 are removed from the oxidant gas. The gas can be discharged to the gas outlet pipe 8. Thereby, it is possible to prevent power generation failure of the fuel cell due to flooding (water pool in the flow path).

  Next, the flow of the fuel gas will be described with reference to FIGS. FIG. 6 is a diagram for schematically explaining the flow of the fuel gas in the fuel cell stack 2. As shown in FIG. 6, the fuel gas supplied from the fuel gas inlet pipe 7 (FIG. 1) flows into the fuel cell manifold 9 from the fuel gas inlet connection portion 61 installed in the middle stage of the fuel cell manifold 9. It is sent to the gas inlet channel 62. The fuel gas is supplied from the fuel gas inlet channel 62 to each unit fuel cell, passes through the fuel gas channel in the unit fuel cell, and is supplied to the anode. At the anode, a reaction in which the supplied hydrogen gas becomes hydrogen ions and electrons (H 2 → 2H + + 2e −) is performed, and the remaining fuel gas without being consumed is discharged to the fuel gas outlet channel 63.

  Here, the flow of the fuel gas in the fuel cell will be described with reference to FIG. As shown in FIG. 7, the fuel gas supplied from the fuel gas inlet channel 62 installed in the middle stage flows through the fuel gas channels 72 installed in the upper and lower parts in the fuel cell 71 and installed in the lower stage. The fuel gas outlet channel 63 is discharged.

  Here, as shown in FIG. 7, the fuel gas outlet channel 63 is installed at a position lower than the fuel gas channel 72 in the fuel cell. Therefore, the flow of the fuel gas is a flow that descends from the fuel gas channel 72 in the fuel cell to the fuel gas outlet channel 63, and water droplets contained in the fuel gas channel 72 are removed from the fuel gas outlet channel 63. Can be discharged.

  Furthermore, as shown in FIG. 6, the water droplets discharged to the fuel gas outlet channel 63 are sent to the fuel cell manifold 9 and discharged from the fuel gas outlet connection portion 64 to the fuel gas outlet pipe 5.

  At this time, since the fuel gas outlet connection portion 64 is installed in the lower stage, the fuel gas outlet connection portion 64 is positioned lower than the fuel gas outlet passage 63. Therefore, the flow of the fuel gas is a flow that descends from the fuel gas outlet passage 63 to the fuel gas outlet connection portion 64, and the water droplets contained in the fuel gas passage 72 are discharged to the fuel gas outlet pipe 5. Can do. This can prevent power generation failure of the fuel cell due to flooding.

  Thus, in the fuel cell stack piping structure 1 of the present embodiment, the cooling water outlet connecting portion 24 that connects the cooling water outlet piping 6 that discharges the cooling water from the fuel cell stack and the fuel cell stack 2 is the fuel cell. Since it is installed at a position higher than the cooling water flow path in the stack 2, the flow of the cooling water discharged from the fuel cell stack can be constantly increased. As a result, the gas mixed in the cooling water passage 32 can be discharged outside the fuel cell without stagnation, so that the cooling performance of the cooling water is improved and the power generation performance and life of the fuel cell stack are improved. (Effect of claim 1).

  Further, in the fuel cell stack piping structure 1 of the present embodiment, the fuel gas outlet connecting portion 64 that connects the fuel gas outlet piping 5 that discharges the fuel gas from the fuel cell stack 2 and the fuel cell stack 2 includes the fuel cell stack. Since it is installed at a position lower than the fuel gas flow path in 2, the flow of the fuel gas discharged from the fuel cell stack 2 can always be a downward flow. As a result, water droplets contained in the fuel gas channel 72 can be discharged outside the fuel cell without stagnation (effect of claim 3).

  Furthermore, in the fuel cell stack piping structure 1 of the present embodiment, the oxidant gas outlet pipe for connecting the oxidant gas outlet pipe 8 for discharging the oxidant gas from the fuel cell stack 2 and the fuel cell stack 2 includes: Since the fuel cell stack 2 is installed at a position lower than the oxidant gas flow path in the fuel cell stack 2, the flow of the oxidant gas discharged from the fuel cell stack 2 can always be a downward flow. Thus, water droplets such as generated water contained in the oxidant gas flow path 52 can be discharged outside the fuel cell without stagnation, thereby preventing power generation failure of the fuel cell due to flooding ( Effect of claim 4).

  Further, in the fuel cell stack piping structure 1 of the present embodiment, the cooling water outlet pipe 6 and the oxidant gas outlet pipe 8 are arranged on the same side of the fuel cell stack 2, so that the cathode outlet that is most prone to flooding occurs. The temperature of the cooling water passing through the vicinity can be increased, and condensation of generated water that causes flooding can be prevented. Further, when each fluid flows in the fuel cell in the horizontal direction, the distance between the stack inlet / outlet manifolds at the left and right ends and the fuel cell external manifold can be shortened, so that weight reduction and cost can be reduced (invoice) Effect of item 6).

  Furthermore, in the fuel cell stack piping structure 1 of the present embodiment, the pipes connected to the fuel cell stack 2 are arranged so as not to overlap each other, so the sensors 13 to 18 are installed above the respective pipes. Space can be secured. In addition, because adjacent pipes are arranged so as not to overlap each other, tool space and hand space can be secured when connecting pipe flanges to the fuel cell case or hose assembly work, etc. This can be shortened (effect of claim 7).

  Further, in the fuel cell stack piping structure 1 of the present embodiment, since the sensor is installed near the connecting portion of the pipe connected to the fuel cell stack 2, the sensor is compared with the case where the sensor is installed on the auxiliary equipment side. Therefore, the impact of pressure loss due to fluctuations in the piping layout after the sensor installation section can be reduced, and the possibility of errors occurring between the sensor reading and the actual value when introduced into the fuel cell can be reduced. The gas value in the fuel cell stack 2 can be accurately controlled by the read value, and the life and power generation performance of the fuel cell stack can be improved. Furthermore, because the sensor's detection unit is faced downward, water can be prevented from accumulating in the detection unit, preventing freezing when left in a low-temperature environment, and gas pressure for power generation in the fuel cell stack. Control failure can be prevented (effect of claim 8).

  FIG. 8 is a perspective view illustrating the configuration of the piping structure of the fuel cell stack according to the second embodiment. As shown in FIG. 8, the fuel cell stack piping structure 81 of the present embodiment is different from that of the first embodiment in that a plurality of fuel cell stacks 82a to 82c are stacked in the vertical direction. Since it is the same as that of Example 1, detailed description is abbreviate | omitted.

  Next, how each fluid flows in the piping structure 81 of the fuel cell stack of the present embodiment configured as described above will be described.

  First, the flow of cooling water will be described with reference to FIGS. FIG. 9 is a diagram for schematically explaining the flow of cooling water in each of the fuel cell stacks 82a to 82c. As shown in FIG. 9, the cooling water supplied from the cooling water inlet pipe 4 (FIG. 8) flows into the fuel cell manifold 90 from the cooling water inlet connection portion 91 installed in the middle stage of the fuel cell manifold 90. To the cooling water inlet channels 92a to 92c of the fuel cell stacks 82a to 82c. Then, cooling water is supplied from the cooling water inlet channels 92a to 92c to the unit fuel cells of the fuel cell stacks 82a to 82c, and passes through the cooling water channels in the unit fuel cells to cool the unit fuel cells. Then, the cooling water is discharged to the cooling water outlet channels 93a to 93c.

  Here, the flow of the cooling water in the fuel cells of the fuel cell stacks 82a to 82c will be described with reference to FIG. As shown in FIG. 10, the cooling water supplied from the cooling water inlet channels 92a to 92c installed in the middle stage of each fuel cell stack is a plurality of cooling water channels installed above and below the fuel cells 101a to 101c. The fuel flows through the fuel cell stacks 102a to 102c and is discharged to the cooling water outlet channels 93a to 93c installed in the upper stage of each fuel cell stack.

  Here, as shown in FIG. 10, the coolant outlet channels 93 a to 93 c are installed in positions higher than the coolant channels 102 a to 102 c in the fuel cells in each fuel cell. Therefore, the flow of the cooling water becomes a flow that rises from the cooling water flow paths 102a to 102c in the fuel cells to the cooling water outlet flow paths 93a to 93c, and the gas mixed in the cooling water flow paths 102a to 102c is converted into the cooling water. It can discharge | emit to the exit flow paths 93a-93c.

  Furthermore, as shown in FIG. 9, the cooling water discharged to the cooling water outlet channels 93 a to 93 c is sent to the fuel cell manifold 9 and discharged from the cooling water outlet connection portion 94 to the cooling water outlet pipe 6. .

  At this time, since the coolant outlet connection portion 94 is installed in the upper stage, it is located at a position higher than the coolant outlet channel 93a of the fuel cell stack 82a installed at the top. Therefore, the flow of the cooling water flows upward from the cooling water outlet channels 93a to 93c to the cooling water outlet connection portion 94, and the gas mixed in the cooling water channels 102a to 102c is transferred to the cooling water outlet pipe 6. Can be discharged.

  Next, the flow of the oxidant gas will be described with reference to FIGS. FIG. 11 is a diagram for schematically explaining the flow of the oxidant gas in the fuel cell stacks 82a to 82c. As shown in FIG. 11, the oxidant gas supplied from the oxidant gas inlet pipe 3 (FIG. 8) flows into the fuel cell manifold 9 from the oxidant gas inlet connection portion 111 installed at the upper stage of the fuel cell manifold 9. From there, the fuel cell stacks 82a to 82c are sent to the oxidant gas inlet channels 112a to 112c. The oxidant gas is supplied from the oxidant gas inlet channels 112a to 112c to the unit fuel cells of each of the fuel cell stacks 82a to 82c, and passes through the oxidant gas channels in the unit fuel cells to the cathode. Oxidant gas is supplied. At the cathode, there is a reaction (2H + + 2e-+ (1/2) O 2 → H 2 O) that produces water by the supplied oxygen, hydrogen ions that permeate the electrolyte membrane, and electrons that have traveled around the external circuit. Done. Then, the oxidant gas remaining without being consumed and the water vapor generated by the reaction are discharged to the oxidant gas outlet channels 113a to 113c.

  Here, the flow of the oxidant gas in the fuel cells of the fuel cell stacks 82a to 82c will be described with reference to FIG. As shown in FIG. 12, the oxidant gas supplied from the oxidant gas inlet passages 112a to 112c installed in the upper stage of each fuel cell stack is a plurality of oxidizer gas installed in the upper and lower portions in the fuel cells 121a to 121c. It flows through the agent gas passages 122a to 122c and is discharged to the oxidant gas outlet passages 113a to 113c installed at the lower stage of each fuel cell stack.

  Here, as shown in FIG. 12, the oxidant gas outlet channels 113 a to 113 c are installed in positions lower than the oxidant gas channels 122 a to 122 c in the fuel cells. Therefore, the flow of the oxidant gas is a flow that descends from the oxidant gas flow paths 122a to 122c in the fuel cell to the oxidant gas outlet flow paths 113a to 113c, and enters the oxidant gas flow paths 122a to 122c. Water droplets such as produced water contained can be discharged to the oxidant gas outlet channels 113a to 113c.

  Further, as shown in FIG. 11, the water droplets discharged to the oxidant gas outlet channels 113 a to 113 c are sent to the fuel cell manifold 9 and discharged from the oxidant gas outlet connection portion 114 to the oxidant gas outlet pipe 8. Is done.

  At this time, since the oxidant gas outlet connection portion 114 is installed in the lower stage, it is positioned lower than the oxidant gas outlet channel 113c of the lowermost fuel cell stack 82c. Therefore, the flow of the oxidant gas becomes a flow that descends from the oxidant gas outlet flow paths 113a to 113c to the oxidant gas outlet connection part 114, such as generated water contained in the oxidant gas flow paths 122a to 122c. Water droplets can be discharged to the oxidant gas outlet pipe 8. This can prevent power generation failure of the fuel cell due to flooding.

  Next, how the fuel gas flows will be described with reference to FIGS. 13 and 14. FIG. 13 is a diagram for schematically explaining the flow of fuel gas in the fuel cell stacks 82a to 82c. As shown in FIG. 13, the fuel gas supplied from the fuel gas inlet pipe 7 (FIG. 8) flows into the fuel cell manifold 9 from the fuel gas inlet connection portion 131 installed in the middle stage of the fuel cell manifold 9. To the fuel gas inlet channels 132a to 132c of the fuel cell stacks 82a to 82c. The fuel gas is supplied from the fuel gas inlet channels 132a to 132c to the unit fuel cells of the fuel cell stacks 82a to 82c, and is supplied to the anode through the fuel gas channels in the unit fuel cells. . At the anode, the supplied hydrogen gas undergoes a reaction (H 2 → 2H + + 2e −) in which hydrogen ions and electrons are made, and the remaining fuel gas without being consumed is discharged to the fuel gas outlet channels 133a to 133c.

  Here, the flow of the fuel gas in the fuel cell will be described with reference to FIG. As shown in FIG. 14, the fuel gas supplied from the fuel gas inlet passages 132a to 132c installed in the middle stage of each fuel cell stack is a plurality of fuel gases installed above and below in each fuel cell 141a to 141c. It flows through the flow paths 142a to 142c and is discharged to the fuel gas outlet flow paths 133a to 133c installed at the lower stage of each fuel cell stack.

  Here, as shown in FIG. 14, the fuel gas outlet channels 133 a to 133 c are installed at positions lower than the fuel gas channels 142 a to 142 c in the fuel cells in each fuel cell. Therefore, the flow of the fuel gas is a flow descending from the fuel gas flow paths 142a to 142c in the fuel cell to the fuel gas outlet flow paths 133a to 133c, and water droplets contained in the fuel gas flow paths 142a to 142c are removed. The fuel gas outlet channels 133a to 133c can be discharged.

  Furthermore, as shown in FIG. 13, the water droplets discharged to the fuel gas outlet channels 133 a to 133 c are sent to the fuel cell manifold 9 and discharged from the fuel gas outlet connection portion 134 to the fuel gas outlet pipe 5.

  At this time, since the fuel gas outlet connection part 134 is installed in the lower stage, the fuel gas outlet connection part 134 is positioned lower than the fuel gas outlet channel 133c of the lowermost fuel cell stack 82c. Therefore, the flow of the fuel gas flows downward from the fuel gas outlet flow paths 133a to 133c to the fuel gas outlet connection portion 134, and water droplets contained in the fuel gas can be discharged to the fuel gas outlet pipe 5. it can. This can prevent power generation failure of the fuel cell due to flooding.

  Thus, in the fuel cell stack piping structure 81 of this embodiment, when a plurality of fuel cell stacks are stacked one above the other, the cooling water outlet connection portion 94 is the cooling water flow path in the uppermost fuel cell stack 82a. Therefore, the flow of the cooling water discharged from each of the fuel cell stacks 82a to 82c can be constantly increased. As a result, the gas mixed in the cooling water flow paths 122a to 122c can be discharged outside the fuel cell without stagnation, thereby improving the cooling performance of the cooling water and improving the power generation performance and life of the fuel cell stack. (Effect of claim 2).

  Further, in the fuel cell stack piping structure 81 of this embodiment, when a plurality of fuel cell stacks are stacked vertically, the oxidant gas outlet connection portion 114 or the fuel gas outlet connection portion 134 is the lowest fuel cell stack. Since it is installed at a position lower than the cooling water flow path in 82c, the flow of the oxidant gas and the fuel gas discharged from each of the fuel cell stacks 82a to 82c can be made to constantly descend. Thus, water droplets such as generated water contained in the oxidant gas flow paths 122a to 122c and the fuel gas flow paths 142a to 142c can be discharged outside the fuel cell without being retained. The power generation failure can be prevented (the effect of claim 5).

  In the first and second embodiments, the pipes connected to the fuel cell stack 2 are arranged so as not to overlap each other. As shown in FIG. 1 and FIG. However, as shown in the fuel cell stack piping structure 151 shown in FIG. 15, it may be arranged so that every other one overlaps the other. The same effect can be obtained with these arrangements.

1 is a perspective view illustrating a configuration of a piping structure of a fuel cell stack according to Example 1. FIG. 3 is a perspective view for explaining the flow of cooling water by the piping structure of the fuel cell stack according to Embodiment 1. FIG. 3 is a cross-sectional view for explaining the flow of cooling water by the piping structure of the fuel cell stack according to Embodiment 1. FIG. 3 is a perspective view for explaining the flow of an oxidant gas by the piping structure of the fuel cell stack according to Embodiment 1. FIG. 3 is a cross-sectional view for explaining the flow of an oxidant gas by the piping structure of the fuel cell stack according to Embodiment 1. FIG. 2 is a perspective view for explaining the flow of fuel gas by the piping structure of the fuel cell stack according to Embodiment 1. FIG. 3 is a cross-sectional view for explaining the flow of fuel gas by the piping structure of the fuel cell stack according to Embodiment 1. FIG. 6 is a perspective view showing a configuration of a piping structure of a fuel cell stack according to Example 2. FIG. 6 is a perspective view for explaining a flow of cooling water by a piping structure of a fuel cell stack according to Example 2. FIG. 6 is a cross-sectional view for explaining the flow of cooling water by the piping structure of the fuel cell stack according to Embodiment 2. FIG. 6 is a perspective view for explaining a flow of an oxidant gas by a pipe structure of a fuel cell stack according to Embodiment 2. FIG. 6 is a cross-sectional view for explaining a flow of an oxidant gas by a pipe structure of a fuel cell stack according to Example 2. FIG. 6 is a perspective view for explaining the flow of fuel gas by the piping structure of the fuel cell stack according to Embodiment 2. FIG. 6 is a cross-sectional view for explaining the flow of fuel gas by the piping structure of the fuel cell stack according to Example 2. FIG. It is a perspective view which shows the structure of the piping structure of the other fuel cell stack from which arrangement | positioning of each connection part differs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 81, 151 ... Piping structure 2, 82a-82c ... Fuel cell stack 3 ... Oxidant gas inlet piping 4 ... Cooling water inlet piping 5 ... Fuel gas outlet piping 6 ... Cooling water outlet piping 7 ... Fuel gas inlet piping 8 ... Oxidant gas outlet piping 9, 90 ... Fuel cell manifold 13-18 ... Sensor 21, 91 ... Cooling water inlet connection 22, 92a-92c ... Cooling water inlet channel 23, 93a-93c ... Cooling water outlet channel 24, 94 ... Cooling water outlet connection part 31, 51, 71, 101a-101c, 121a-121c, 141a-141c ... Fuel cell 32, 102a-102c, 122a-122c ... Cooling water flow path 41, 111 ... Oxidant gas inlet connection Part 42, 112a-112c ... Oxidant gas inlet channel 43, 113a-113c ... Oxidant gas outlet channel 44, 114 ... Oxidant gas outlet Connection part 52, 122a-122c ... Oxidant gas flow path 61, 131 ... Fuel gas inlet connection part 62, 132a-132c ... Fuel gas inlet flow path 63, 133a-133c ... Fuel gas outlet flow path 64, 134 ... Fuel gas Outlet connection part 72, 142a-142c ... Fuel gas flow path

Claims (8)

In the fuel cell stack piping structure for supplying fluid to the fuel cell stack,
The cooling water outlet pipe for discharging the cooling water from the fuel cell stack and the cooling water outlet connecting portion between the fuel cell stack are installed at a position higher than the cooling water flow path in the fuel cell stack. Piping structure of fuel cell stack.   2. The fuel according to claim 1, wherein in the configuration in which the fuel cell stacks are stacked in a gravity direction, the fuel cell stack is an uppermost fuel cell stack of the stacked fuel cell stacks. Battery stack piping structure.   The fuel gas outlet pipe for connecting the fuel cell stack and the fuel gas outlet pipe for discharging the fuel gas from the fuel cell stack is installed at a position lower than the fuel gas flow path in the fuel cell stack. The piping structure of the fuel cell stack according to any one of claims 1 and 2.   The oxidant gas outlet pipe for connecting the oxidant gas outlet pipe for discharging the oxidant gas from the fuel cell stack and the fuel cell stack is installed at a position lower than the oxidant gas flow path in the fuel cell stack. The piping structure of the fuel cell stack according to any one of claims 1 to 3, wherein the piping structure is a fuel cell stack.   5. The fuel cell stack according to claim 3, wherein the fuel cell stack is a lowermost fuel cell stack of the stacked fuel cell stacks in a configuration in which the fuel cell stacks are stacked in the direction of gravity. A fuel cell stack piping structure according to claim 1.   The fuel cell stack according to any one of claims 1 to 5, wherein the cooling water outlet pipe and the oxidant gas outlet pipe are arranged on the same side of the fuel cell stack. Piping structure.   The fuel cell stack according to any one of claims 1 to 6, wherein each connection portion of the fuel cell stack is arranged so that adjacent connection portions do not overlap vertically. Piping structure.   8. The piping structure for a fuel cell stack according to claim 7, wherein a detection means with a detection portion facing downward is installed in the vicinity of each connection portion in the piping connected to the fuel cell stack.

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